Receptors for acetylcholine at skeletal neuromuscular junctions and homologous synapses in electric tissue transduce the binding of acetylcholine into changes in cation permeabilities. The overall goal of this project is to determine the mechanism of the function of these receptors in terms of their molecular structures. The immediate goals are the size and shape of receptor in detergent solution and in native membrane, the arrangement of receptors in the membrane, the primary structural characteristics and stoichiometry of the subunits of the receptor, the arrangement of the subunits in the receptor, and the contributions of the individual subunits to receptor function. The techniques which will be applied include neutron scattering analysis, analytical ultracentrifugation, electron microscopic immunohistochemistry, chemical cross-linking, affinity labeling, labeling by impereant reagents, and peptide mapping. Comparisons will be made principally between the receptors from the electric tissues of Torpedo californica and of Electrophorus electricus.